Reptisuns havent had to be changed out every six months since they (and arcadia) switched to T5HO. Before that yea "shade" T8 bulbs didnt put out much, so after 6 months, even less of not much.
I run both arcadia and repti sun, and i cant tell the difference with my solar meter. They seem to drop to half output after 2 years, and i rotate them out into "daylight" bulbs or the 10.0's get rotated into the 5.0 cages.